[Amps] UHF Connectors

[Roger (K8RI)]

On 11/13/2013 7:29 AM, Paul Christensen wrote:
>> I've given up on the traditional solder-type PL-259s. Now I use the
>> crimp on
>> type and have never had a failure. The crimper is expensive but well
>> worth
>> the time and hassle saved.  I got both crimper and connectors on eBay.
>> There
>> are many sizes so be sure you get the right ones.
>
> I started using crimps for indoor installations.  Outdoors, I still
> prefer soldered PL-259s.
>
> All inside cabling is RG-400.  The crimps have held up well except for
> one recent failure:  The connector body had separated from the ground
> sleeve end that's inserted onto the braid.  What's strange is that since
> the crimp is still strong and intact, the connector looks fine to the
> eye -- but the body now rotates when the sleeve is held firm.   These
> are high-quality crimped connectors from Amphenol.

I've never had it happen with Amphenols, but I have had crimp UHF 
connectors with a lot of side force break.

IIRC the the sleeve and body are held together with a simple flare 
crimp, for lack of a better name.

(the sleeve has a slightly smaller OD at the end. this id a press fit 
into the body and extends through the body so the end can be flared 
slightly. It's a tiny amount, but normally grips well)

  If enough side pressure, or torque is applied, I would think it could 
fail in the manner described. That is if the connector is assembled in 
the manner I think it is.  UHF connectors are not meant to hold much 
load, so mechanically I'd not expect the physical structure to be 
designed to hold much either.

With LMR-600, this is a weak point and the larger cable can present much 
more of a mechanical load to the connector. I've had them break off 
completely at this point.  That may be one of the reasons why the UHF 
connectors for LMR-600 are so much more expensive. That and they are a 
low volume product in comparison.

I need to dissect a connector to see just how they are constructed. If I 
can do it neatly enough I'll put up a file.  If I could figure how to 
mount the cut off tool in the mill, I should be able to get a clean cut. 
  They do make thin cut off saws for the mill, but the arbor and blade 
are kinda pricey to just cut some connectors apart as an experiment. 
You can easily spend more on accessories in a machine shop than for ham 
radio and quickly if you want to do much. <:-))

>
> The crimp worked so well that the connector is actually usable until I
> cut it down and install a new connector.  Not sure how this happened.
> The PL-259 is installed on the back of a transceiver and because it's
> protected in a deep compartment, there's little chance that it

Could be the bending force if the LMR-400 was not bent before it was 
connected?  I can only guess at this point.

> could.have bumped into something and broken that way.

It doesn't normally take much leverage to break one loose, or off 
relatively speaking.  OTOH it's not something I'd normally expect.
I would pitch such a connector though as that represents a possible high 
resistance joint, even if it handles little current.

73

Roger (K8Ri)

>
> Paul, W9AC


>
>
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